What's wrong with moderation? Day-to-day navigation elements shouldn't be in a hamburger menu (also, an extra 'click' for common tasks is bad), but there are plenty of non-everyday things that can go in there.
You're blaming designers , I'm blaming developers(and managers) who can't tell a good designer from a bad one and choose to work only with people that "gravitate to extremes in these fads"(ie a majority of startups) Even Google and Apple are not that dumb, they know flat design is stupid,they actually have the data to prove it, thus they kept some depth within their UIs and don't hesitate to use border shadows ,even on mobile, while trying to "refresh" their UI, because a few influential SF bloggers were bashing their "lack of minimalism".
Flat design makes absolutely no FN sense, from a UX stand point in an app on a computer. If I can't tell what I can interact with and what I can't, I'm not going to play a guess game, I'm going to move on and use something else. I'm a big proponent of skeuomorphism and I don't care how ugly it looks. It's all about usability. If it can help convey the purpose of a feature then it's a good thing.
What makes sense on a poster, a printed magazine or a book doesn't make sense for an app or a website.